


Baby Sebastian

by Myworldofgayfanfiction



Category: Marvel Cinematic Universe RPF
Genre: Accidents, Bouncers, Cribs, Daddy!Chris, Diapers, Little!Sebastian, M/M, More tags to be added, Non-Sexual Ageplay, Pacifiers, Playfull Fighting, Uncle!Rdj, Whining, bottle feeding, naps, should I continue this?
Language: English
Status: In-Progress
Published: 2018-10-18
Updated: 2018-10-23
Packaged: 2019-08-03 16:05:18
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 3,217
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16329194
Author URL: https://archiveofourown.org/users/Myworldofgayfanfiction/pseuds/Myworldofgayfanfiction
Summary: A day in the life of Sebastian Stan and Chris Evans but with a little twistYou get what I’m saying?





	1. Chapter 1

 

 

Chris woke up to soft crying from the nursery next door to his bedroom. He smiled slightly and got up, rubbed the sleep out of his eyes, put on a clean pair of boxers and left his bedroom to enter the nursery were a little Sebastian was standing up in his crib in a red onesie with a captain America (“Daddy! It looks just like you!”) pacifier bopping I’m his mouth. 

Chris cooked at the sight of his baby and went over to him, lightly pushing him back down onto his bum so he would sit down and ran his hands through his hair 

“Good morning my prince, how are you this morning?” He cooed as Sebastian put his cheek on the blinds hand and looked up at him with big blue dow eyes. 

“Are you wet, baby?” He smiled and took down the cribs bars, taking the baby out and putting him on his hip, then grabbing nelly (Sebbys pink elephant) and giving her to the boy, who took it and smiled 

“da” He said from behind the paci and tucked his head into the crook of Chris’ neck. Chris patted the baby’s padded bottom and laid him down onto the changing table. And of course Sebastian had to wriggle around 

“Sebastheheian! Stop wriggling you little donut!” Chris chuckled and quickly unzipped the onesie while the baby was laughing “Donuts get eaten!” Chris grinned and leaned down, blowing a raspberry on the baby’s belly, making him squeal and laugh, kicking in every direction he could without hurting Daddy 

“Daddyyyy! Stohohoahahahp!” He continued to squeal. Chris stopped and looked up at his baby, leaning over him and rubbing their noses together.

”Your so cute” Chris smiled as Sebastian nodded in agreement. Chris laughed at that and leaned up-right again, changing the boys nappy and then looking down at him 

“Daddy! Clothes!” Sebby pointed to his almost naked body and squirmed, his paci still bopping rythmatically. 

“Nope. Just gonna let Uncle Downy See you like this” He grinned as Sebastian whined and blushed in embarrassment. 

“No daddy!” He whines and Chris laughed, quickly pecking the boy on the cheek 

“I know, I know, I wouldn’t really do that baby!” He went into the closet and picked out an adorable dragon onesie, made from soft and fluffy material with little spikes on the back and ears on the hood. “Baby want this one?” Chris asked and to which Sebastian nodded eagerly.

* 

A few hours later, Sebastian had eaten and was now playing on the play mat in the living room. He had his cars, trucks, Blocks and of course, Nelly. 

Sebastian made a little tower for Nelly out of blocks and was now driving the elephant in one of the bigger trucks to the ‘cave of wonders’ which was really just the space between the sofa cushions on the couch. 

“Havin fun, baby?” Chris, who had been watching him, asked and Sebastian nodded, making car noises as he drove the truck up Chris’ leg. Chris grinned and jogged his leg a bit, making Sebastian’s hand slip and let go on the truck. Sebastian giggled and grabbed Nelly from under the truck, hugging her close 

“Is Nelly hurt?” Chris had to double check. 

Sebastian shook his head no and climbed up onto the sofa.. well he tried to but failed and fell onto his bum. He huffed and put his arms up and made grabby hands at daddy 

“Uh oh! Looks like someone is a bit bouncy today” Chris smiled and picked the boy up, going over to the bouncer and placing Sebastian into it, then sitting infront of him and making him bounce. Sebastian started to play with the little buttons on the front but of the bouncer, kicking his legs in delight as they made noises. 

Chris smiled at the purely happy look on the baby’s face, then kissing his cheek and pressing the buttons with him, making the noises funnier as they mixed together. Who knew the mix between ‘cat’ and ‘frog’ was so funny? It was then that Chris realised it sounded like ‘fuck’ and couldn’t stop laughing, Sebastian doing the same as he realised what it said. 

“Bouncer said bad word, daddy!” Sebastian laughed out and as Chris nodded and wipes his eyes from tears of laughter. 

“That’s right baby it did! We don’t repea-“ Chris got cut off by his own snort which made Sebastian and Chris himself start to laugh again. 

“Piggy laugh!!” Sebastian laughed out again. God the bouncers werent supposed to be this funny! 

Suddenly, there was a knock on the door and Sebastian gasped in joy, stopping his full on laughing to small happy giggling, bouncing himself accidentally as he kicked his legs with his arms up towards the door. 

Chris got over the snort and the naughty word and got up, still smiling like a goon as he opened the door to reveal Rdj. 

“Hey, Robert!” Chris smiled and hugged him. Downy hugging him back and winked as he saw the baby in the bouncers 

“hey man! Hope I wasn’t interrupting play time” He grinned and followed Chris into the living room 

“No, Sebastian and I were just playing with the bouncer” He smiled and picked his baby up, putting him on his hip and kissing his cheek 

“Nice, hey little buddy! Miss your favourite uncle?” Downy said and ruffled Sebastian’s hair. Sebastian whines and put his arms out towards the brunette. Said Male chuckled and took the baby into his arms, hugging him tightly and then putting him on his hip. 

“Da da!” He nodded enthusiastically and smiled. Sebastian then looked at Chris and pointed at his paci. 

“Such a needy baby” He rolled his eyes and grabbed the pacifier, putting it close to Sebastians mouth but pulling away when he went to take it “Ah ah, what do we say?” 

“Vā rog!” He smiled and grabbed it when it was closer to him 

*

The rest of Then day was fun, Rdj played with Sebastian. A lot of play fights that Chris gave up warning Rdj about hurting his baby. And he never did obviously. Because Rdj would go back to old habits if he ever even grazed the baby. Because Sebastian doesn’t  (never did, never shall) deserve just the tiniest bit of sadness. He deserved everything and everything. 

They made cookies together which ended up with Chris having a lot of cleaning up to do tomorrow either before Seb woke up or while he was playing. The kitchen was just a mess of plates, flour, bowls, spoons, cookie cutters and so on. 

Sebastian only had only wet 2 times which was good because he was getting better at using his diaper. Yeah, it was ever so slightly still awkward because although Chris had seen and touched Sebastian’s parts, it was an odd feeling of your boyfriend changing you into a diaper. But Sebastian wouldn’t ever change ageplay just for slight embarrassment! Not ever ever would he leave his daddy! 

So all in all, the whole day went well! Except when Robert had to leave. 

* 

“NOO!” Sebastian screamed for the how-ever-many time from his place on Chris’ hip. The boy kicked his legs and shook his head, not wanting uncle Downy to leave. 

“Oh baby boy, it’s okay! I will see you next weekend right?” He smiled and kissed Sebastian on the cheek. Chris bounced the baby in his arms to just get something out of the baby except a Romanian swear or the word No screamed out from the top of his lungs. 

“Noo..” He mumbled and grabbed Rdjs hand, squeezing it and burying his head in the crook of Daddys neck. 

After that, Chris and Rdj said their own goodbyes, Rdj sent his luck to Chris with the baby and Chris just smiled and nodded in thanks. Then, Rdj was pulling out of his car and going off back to his own house. 

“Baby it’s okay, I’m still here” Chris kissed the top of the baby’s head and walked over to the mess that he was still trying to call a kitchen in his own mind. Chris grabbed Sebastian’s bottle for his nap and took that and ye baby into the nursery. Chris sat down onto the rocking chair and laid the baby down comfortably. 

“Say ‘ahh’ Sebastian” Chris said softly and quietly, shaking the bottle infront of the baby’s face. Sebastian’s cry’s died down a bit as he saw the bottle, sniffling and then making grabby hands at it. Chris chuckled and dipped the bottle into the baby’s mouth, holding onto it as Sebastian placed his hands over Chris’ and looking up at him with the most trust worthy look on his face. Chris smiled and so did Sebastian, making him dribble and that dribble going onto Chris’ jeaned leg. But Chris didn’t care. Chris has been puked on by the baby before (Chris’ fault entirely because he made the baby eat more than he could) so Chris just really didn’t care about some dribble. 

After the bottle was finished, Sebastian was into a deep sleep, one that you don’t wake up from for what feels like forever. Chris then picked his baby up bridal style and laid him down in the cot, tucking Nelly close to him (it didn’t leave his side all day) and covering him in a blanket, then putting the baby mittens over his hands and feet, making his baby nice and warm for his sleepy time. 

* 

Chris sat on the sofa and wondered 

why was Sebastian so riled up that Rdj was leaving? 

Sure, when Rdj came over and hung out with Chris and his baby, Sebastian would snuggle and but and be sad that Rdj had to leave it he never screamed or kick or practically move other than his chest from his breathing. 

Then, Chris went through his emails. 

They were to start filming Monday. Today was Saturday. 

 

 

 

 

 


	2. Filming

**Summary for the Chapter:**

> Sebastian and Chris have to start filming and Sebastian is very little.

**Notes for the Chapter:**

> They are not filming a marvel movie because Sebastian isn’t as muscled as he should be to play Bucky. 
> 
> NO HATE TOWARDS TINY SEBASTIAN, HE IS ADORABLE!

 

 

“Good morning, little one” Chris smiles slightly sadly as he knew Sebastian wouldn’t go well with having to go into big-Sebastian mode. 

“Daddy” Sebastian whined as he saw the mittens on his feet and hands. Sebastian wasn’t a big fan of them. 

“I know baby, I’ll take them off now” He picked the baby up out of the crib and placed him into the changing table, taking the mittens off and putting them away. Chris tickled Sebastian’s foot as he took the last one off, making the baby giggle and try to get away. Chris then quickly changed him into a clean diaper. Yes, Sebastian wasn’t a real baby all the time but his body was obviously different from his mind as he would still use a diaper while big. 

“Baby.. you gotta be big boy Sebastian today” Chris tried to say as friendly as he could but Sebastian just whined and shook his head, tears pricking at his eyes 

“Oh baby it’s okay, it’s just for today” That was a lie. It would probably be about 7 months or so. Chris felt evil for lying but he had to. The only people who knew were Rdj and Chris’ brother Scott (He would sometimes help if things got really bad) 

“No daddy!” He cried and crossed his arms “Don’ wanna!” He kicked slightly and Chris had to grab his ankles lightly to make him stop. 

“Hay now, no kicking. We have to film baby, okay? I need you to be big today” He kissed him on the head and let Sebastian cry. Sometimes the baby just had to let out a cry and now want Chris to help him. It wouldn’t be because he was sad, just felt the need to let go and that’s exactly why ageplay was such a good thing for Sebastian because he could just let go for a while and let Chris take over. But now, Sebastian needed to be big and Chris always hated it but he knew that comforting Sebastian wouldn’t help. 

A few minutes later of the boy crying, Sebastian had aged up and was now sitting, grumpily, in the front seat of the car, arms crossed and lips pouting as the people on the radio talked. 

“Your not that mad at me, are you?” Chris said, breaking the awkward silence. 

Sebastian just shrugged and looked out the window. Chris sighed and shook his head. 

“I’m sorry. I know you want to be Little but we have to film” He places his hand onto Sebastian’s knee, patting. 

“I know..” Sebastian grumbled. Chris sighed sadly again, stopping at the red light and reached his hand up to Sebastian’s stomach, tickling him. Sebastian squealed, kicked his legs and flailed his arms, trying to get Chris’ hand away. 

“Chris! Green light!” Sebastian laughed out. Chris’ head shit to the green light and he stopped tickling Sebastian, going back to driving and grinning as he continued to hear his boyfriend giggle. 

* 

When they got to set, they went to hair and makeup first, of course Sebastian only grumbled and whined ans let Chris just do all the talking but Chris was kinda to blame for his behaviour. 

It was when they got onto set and Sebastian saw Rdj that Seb gasped and smiled brightly, running over to the other brunette and hugging him tightly, happy to see his unc- best friend who just so happened to be a family member when Sebastian was in a certain mind frame. 

“Hey, Seb!” Rdj hugged him back and had to pull him away just so he could see him. He really did feel bad for having to leave and was still curious on why the baby was so more-than-usual worked up. “You doin okay now?” He looked Sebastian in the eyes and could just see it. See the wanting to be little past the fake adult-ness in those blue winter eyes. 

Sebastian shrugged and bounced a little, grinning as he got to see his uncle- best friend again! 

Chris came up to them both and he pulled Sebastian away so Rdj could continue filming. Sebastian only watched Rdj act amazingly and grin at how he would get to play with him later! 

“Daddy.. can me and Rdj play?” Sebastian whispered before he even registered what he was saying. Chris tended slightly and sighed, shaking his head and pulling Sebastian to the bathroom. 

“Sebastian, I need you to be big. Your gonna have to be big for a while now because of filming, okay?” Chris tries to explain to the giddy Sebastian. She just kept bouncing off the walls and thinking to himself “Okay?” He tapped Sebastian on the temple a bit harshly and the boy looked up at him “I need big Sebastian now” 

Anothe bout of crying, another bout of grumpy Sebastian. 

* 

Lunch was a nightmare. Rdj and Chris tried to make Sebastian eat (Sebastian was in the middle of them) but to no avail as he only pushes away the food. They couldn’t feed him. No, that would be to obvious. But the three were getting odd looks from the crew most of the lunch break which probably didn’t help Sebastian anxiety. 

Sebatsian ate about 3 fork fulls of salad and nothing more. And Chris just felt even more guilty for it.

* 

Sebastian was great at acting his character (William, his name was) But it was between takes that Sebastian would go out of character for the slightest of second to just glare or huff or sigh at either Rdj or Chris. Sebastian even made small tiny grabby hands at his dadd- Chris as he was on set too. Chris smiled sadly at him and just like that, they were back into character as they started rolling again. 

 

 

 

 

 


	3. Breakdown

 

 

It was the 4th week in Of filming that Sebastian broke down. Thankfully it was in his trailer away from others but it wasn’t so good that Chris wasn’t there at the time. So when Chris realised Sebastian wasn’t at lunch, he went to check on him. 

“Sebastian? Love can you open the door? It’s cold” Chris called out as he tried to open the locked door to Sebastian trailer. 

Suddenly, the trailer door swung open, but Sebastian wasn’t standing at the door, he was sat on his knees, crying his eyes out with a wet patch around his crotch. 

“Sebastian? Oh baby boy” He said softly and picked him up, going into the trailer and shutting the door. Chris sat on the sofa and laid Sebastian over his chest, shushing him. 

“Baby I’m so sorry” Chris shushed him as he held him tight, not really caring about his clothes “This is all daddy’s fault, baby” He kissed to top of Sebastian head and rocked him. 

“Daddy..” Sebastian sobbed out as he held tightly to Chris. 

“Shh your alright now, shhh” He continues to rock his baby, feeling like shit for putting Sebastian through this. 

Lunch could wait. 

His baby needed him. 

* 

It took a total of 25 minuets to calm Sebastian down so Chris could change him. Now, Sebastian was laying on the sofa in Chris’ jumper with a blanket draped over him. 

Chris held Sebastian’s hand as he croutched next to the baby, rubbing the back of his smooth small hand with his thumb, gliding over his knuckles as he smiled at Sebastian. 

“You alright now baby boy?” Chris asked in a sweet and soft voice, one that Chris normally used when he was this little. After a breakdown, most littles went younger than they normally were. So Chris guessed that Sebby was younger than usual, which was okay because Chris didn’t mind what mental age the brunette was, he would still love him endlessly.

Sebastian shrugged as he looked up at the ceiling of the traylor, tired from the break down and tired from filming in general. They had a few months left (that felt like it was years to both of them) and then everything would go back to normal again. Sebastian really liked that thought. 

“You hungry? I can get some food and bring it back here if you like” Chris said softly again, kissing the baby’s knuckles as he yawned and nodded yes to Chris’ question “Alright, I’ll get something. Will you be okay on your own?” Chris said as he started to stand up, still looking at his baby as he did. 

Sebastian shrugged again and continued to avoid eye contact. Chris gave him the ‘are-you-Sure-Your-not-lying-to-me?’ Look and Sebastian doesn’t seem phased by it, probably either hasn’t seen it or just is too tired to care. Chris didn’t know if it was the former or the latter, now. 

“Sebastian..” Chris’ voice goes stern but friendly at the same time “Tell the truth, Sebastian” Chris crosses his arms over his chest 

Sebastian fiddled with his hands, not looking at Chris as he shook his head “Don’ wanna be ‘lone, Daddy” He sniffles and shivered, even though he wasn’t cold under the soft and fluffy blanket. 

Chris sighed and nodded “That’s okay baby” He crouched next to him again “But you have to get some food into your little tummy” He tickled his baby’s tummy at that, making him giggle and finally look up at his daddy. 

Then, Chris had an idea. 

This was either going to work, or possibly maybe sorta kinda not. 

 

 

 

 

**Notes for the Chapter:**

> Ooooo cliffhanger ;)


End file.
